Which receiver (Pioneer or Yamaha) for LSi-15

nguyendot

ravaneli wrote: »

Ok, so we established that if you want to output the same Watts as with 8-ohm speaker you need 41.4% more current. But how much do you reduce the volume (in db) so that the current is what it used to be with the 8-ohm speaker?

Well since the decibel is a ratio between two powers we need to see what happens to the watts if we use the 4 ohm but the old current. So instead of W(P0) = 1.41 I^2 x 4 we want to calculate W(P1) = I^2 x 4.

Well P0 = P1 x 2 so

P1 = 1/2 P0

That means that if you plug 4 ohm speakers and want to keep the current to the levels of the 8-ohm speaker, you have to reduce the watts IN HALF. So if your AVR could safely push 100W @ 8 ohm, it can only push 50W at 4 ohm.

How do u reduce the power in half?



P1/P0 = 1/2

Ldb = 10 Log10 (1/2) = 10 x (-0.3) = -3 db

So reducing the volume by 3 db will half the power output of the AVR and will ensure you are at the old current levels.

You factor in that the 4 ohms is not a static rating? Also that is with a tone. Send music through and the volume, and therefore current / impedance will swing.

Geoff4rfc

brentba wrote: »

Once again, please allow me to explain myself because posts like tommyt21's make it clear that I am being misunderstood.

I am in NO WAY against purchasing a 4-ohm capable amplifier. In fact, I agree 100% that this is the best way to get the most out of the Polk LSi speakers. I fully intend on purchasing an amplifier in the very near future.

My intention for starting this thread was not to start a discussion on whether or not it is safe to power 4-ohm speakers with an A/V receiver.

Right, it was a question of which AVR would be better suited to drive the LSi's. IMO, the Pio, the more power, the better. But just because the AVR is rated at 4ohm, should you? Probably not as the one poster with the Onk 709 stated repeated shut downs because of it.

brentba wrote: »

A lot of this thread has been devoted to bashing ravaneli. However, regardless of the accuracy or inaccuracy of his technical claims, he is the only one who seems to understand my position (based on his most recent post). I kind of feel bad for the guy (although I guess I haven't gotten to know him as well as the rest of you).Brent

And you will (get familiar with his posting style). It's no secret, unless you're fairly new, that ravioli will repeatedly post ludicrous, outlandish and hilarious statements, and will repeatedly contradict himself in a single post as well as through an entire thread. So when the ravioli ferris wheel starts up, it's difficult not to jump on and go for the ride. I refrain from too much invovlement since he loves to call me a stalker.

ravaneli

lol, brentba, don't feel sorry for me, mate : ) These poor souls have nothing on me. I can take twice their number. If I cared any about them liking me I would be a spineless conformist like geoff and agree with everyone and approve of everything and always go with the crowd.

I am not even arguing with them. It is when new people like u come and they try to sell the same old **** when I get a tick. I am surprised there is not a single engineer here to put an end to all of this. How can we argue for things that are provable mathematically is beyond me. Their answer to ANY question posted here from a noob (no pun intended) is SPEND MONEY. They never present the poster with an accurate picture. Often the gear the poster has is good enough to hold him for a while, if used properly. Often they go into misleading people into what they will get. These expensive amps are always described to have this magic qualities when the best an amp can do i reproduce the input. Wires, tubes.. shams left and right.

cstmar01

ravaneli wrote: »

lol, brentba, don't feel sorry for me, mate : ) These poor souls have nothing on me. I can take twice their number. If I cared any about them liking me I would be a spineless conformist like geoff and agree with everyone and approve of everything and always go with the crowd.

I am not even arguing with them. It is when new people like u come and they try to sell the same old **** when I get a tick. I am surprised there is not a single engineer here to put an end to all of this. How can we argue for things that are provable mathematically is beyond me. Their answer to ANY question posted here from a noob (no pun intended) is SPEND MONEY. They never present the poster with an accurate picture. Often the gear the poster has is good enough to hold him for a while, if used properly. Often they go into misleading people into what they will get. These expensive amps are always described to have this magic qualities when the best an amp can do i reproduce the input. Wires, tubes.. shams left and right.

According to who you? The biggest thing that a lot of people here state is to try it yourself. There are different levels of how serious you want to get with the hobby. Some just want to do something once and be done, others like to explore and are looking for advice. Whats annoying is when you tell people they are wasting their money when they want to try something.

Its funny, one who claims that others attack him yet you have done your own fair share. I'm still waiting for you to post what reference system you have that compares to the McIntosh, Krell, etc that you must have compared them all to.

Geoff4rfc

ravaneli wrote: »

If I cared any about them liking me I would be a spineless conformist like geoff and agree with everyone and approve of everything and always go with the crowd.

Do you have actual experience with that statement or did you just read it in a review? I certainly don't confirm to any you have to say.

ravaneli wrote: »

I am not even arguing with them.

You argue with 99% of the posters in every thread you post in, how are you going to say that? Oh yeah, I forgot, you contradict yourself on a routinely.

ravaneli

geoff, why don't u go learn something and for once in your life come with independent position.

txcoastal1

So Rav, I guess everyone is wrong, you are always right, and we are suppose to follow your independent thoughts.

PolkieMan

Doesn't speaker impedance change at different frequencies?
It's been over a year I have been running 2.3tls with a Onyko NR-808
but it sits on an open stand and I don't play it real crazy loud.

pyrocyborg

PolkieMan wrote: »

Doesn't speaker impedance change at different frequencies?
.

Yes it does. Take a look at this graph (LSi9):
impedance.gif

As you can see, the LSi9 can dip as low as 2 ohm, but is generally between 4 or 5 ohm accross the frequency range. So yeah, you're right, impedance isn't static at all.

However, if the current power usage isn't that high at, for example, 8 ohm, it won't be crazy high at 3 ohm for certain frequencies: that's why you do not seem to have any problem now, and it'll be like that as long as your speaker do not demand more power during "spikes" than your amp can give it.

Also, correct me if I'm wrong, but I think that the 2.3tls are a little bit higher than 4 ohm... as many manufacturers prefer to be safe on these kind of ratings (e.g. Polk with the LSi7 which could be rated at 6 ohm instead of 4).

ravaneli

nobody is always right, but am I always wrong is the question. Every time i stray from what is considered mainstream here everyone jumps the guns. Then everybody thinks they got the language skills to flip the issues upside down and depict me as always right. ' so, rav you are always right, huh?' Isn't this the lamest attack? If you want to point where particularly i was wrong - go ahead. Otherwise save these cheap lines for the fights with your spouse. 'you always right,huuh?' No, im not always right. It's just that when I agree there is no argument. As a matter of fact I agree with posters most of the time. But every time I disagree, a big thing unfolds, because THOU SHALT NOT DISPUTE THE MYTH.

PolkieMan

Wow it really gets high at about 30Hz so it would seem since there is more resistance that it would not be as loud at say 40 down to 25 and of course below that there isn't much material anyway so 40 would be the roll off point.

"As you can see, the LSi9 can dip as low as 2 ohm, but is generally between 4 or 5 ohm accross the frequency range. So yeah, you're right, impedance isn't static at all"

F1nut

ravaneli wrote: »

nobody is always right, but am I always wrong is the question.

Yes.

brentba

The LSi-15s were delivered today (refurbished stock from Polk's ebay site). They were packaged like brand new and not a single mark on them. They're perfect!

I've been listening to them all afternoon. They sound great despite the Yamaha RX-V867 A/V receiver. I'm really looking forward to feeding them some real power in the near future.

I've been listening at a comfortable level for the past several hours (-25.0 to -20.0 on the receiver, if that means anything). They Yamaha is still running fairly cool.

I haven't seen the LSi's in person in a while. I forgot how sexy they are :cheesygrin: